From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76A18C04AAF for ; Tue, 21 May 2019 08:02:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AB63217D4 for ; Tue, 21 May 2019 08:02:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="U5lZgDhD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727253AbfEUICn (ORCPT ); Tue, 21 May 2019 04:02:43 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:35347 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727205AbfEUICl (ORCPT ); Tue, 21 May 2019 04:02:41 -0400 Received: by mail-wm1-f66.google.com with SMTP id q15so1819773wmj.0 for ; Tue, 21 May 2019 01:02:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=DOhhDvGFx5TQBrV3vUuuJNqU81qFULp2qAUcY70tdpo=; b=U5lZgDhD03GpNQCNQxmESbv9lWfJZcDrizZYolBCQqWW/xEYt9UwLILokyg8eZw2fv OoHDixUXEs4MfaUj9VCaYKeLQ6CgxSEf+3dN3WetIPP+SUCRY7n1qJjhUO9i7So752mT eOVjY3sdJA+kTXkPvE52Mc0lf6Qz9kuRXbijZTvxFeFXk/rtACX7jccmZp1RgxGZpYNb R8icSFl8ioKe7x+3GqeaG1+kGo2RQ5tP0EH7tAtsrz9RlLQT0gbcEiXM0C89oq41RMxJ 131Ipwk/vsUv5tD+3ALHha2SVRHMkreikP5BaMJXOjM6YlJ28mWz/Gj0x3kuklYPyrNb hU3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=DOhhDvGFx5TQBrV3vUuuJNqU81qFULp2qAUcY70tdpo=; b=uWi0SfaGdtcIwvpx2EIDGiay5Q0O6SIhoDJiXpJo2n6KIbPdma+ZxbPzv/DD+FPppj ngiNUWx6RL49T5a7Vm1i5aGs87ik5cVDMTstLDF/+rYxVdz0E2X0TG9GAWnbgRkjFeyc cQAibQLqGaNWY1MkA6dVpt8ON5h/ysh1vPPmwFmWFk6rlZEXUn7JEfz4T2q4+Nmi8Vqe 2sUo6995yJiK2flNS0pMBpFvQ6ccdIfznuNu6FY7uJIYXq8ElZy3YJdAcCyg1vWVYWLe XxbCc5aTe6ftQuOGZjcO7pbJL2D22haquYIa+HtgWwiOWjlTzm4sJz5X1MDWSUHCqPpP HCsg== X-Gm-Message-State: APjAAAVrVlaokdjzURsuR4IrR/Qbfm4TYXaxmjkqgKgCHJ4QPPCFeCP0 22obsxJaTs4/uWiZpIAZ8e8Yiw== X-Google-Smtp-Source: APXvYqyspoPg9SEqm8OAK4EKMduyZ0wkoaz46tnzvrFz0D5YKN4kzgcvCqAOYUkBdjzY7BugddgXkw== X-Received: by 2002:a1c:3287:: with SMTP id y129mr2330502wmy.153.1558425759355; Tue, 21 May 2019 01:02:39 -0700 (PDT) Received: from localhost.localdomain ([88.147.35.136]) by smtp.gmail.com with ESMTPSA id p8sm11322301wro.0.2019.05.21.01.02.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 May 2019 01:02:38 -0700 (PDT) From: Paolo Valente To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org, bfq-iosched@googlegroups.com, oleksandr@natalenko.name, Angelo Ruocco , Johannes Thumshirn , Paolo Valente Subject: [PATCH 2/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter Date: Tue, 21 May 2019 10:01:55 +0200 Message-Id: <20190521080155.36178-3-paolo.valente@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190521080155.36178-1-paolo.valente@linaro.org> References: <20190521080155.36178-1-paolo.valente@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Angelo Ruocco Many userspace tools and services use the proportional-share policy of the blkio/io cgroups controller. The CFQ I/O scheduler implemented this policy for the legacy block layer. To modify the weight of a group in case CFQ was in charge, the 'weight' parameter of the group must be modified. On the other hand, the BFQ I/O scheduler implements the same policy in blk-mq, but, with BFQ, the parameter to modify has a different name: bfq.weight (forced choice until legacy block was present, because two different policies cannot share a common parameter in cgroups). Due to CFQ legacy, most if not all userspace configurations still use the parameter 'weight', and for the moment do not seem likely to be changed. But, when CFQ went away with legacy block, such a parameter ceased to exist. So, a simple workaround has been proposed [1] to make all configurations work: add a symlink, named weight, to bfq.weight. This commit adds such a symlink. [1] https://lkml.org/lkml/2019/4/8/555 Suggested-by: Johannes Thumshirn Signed-off-by: Angelo Ruocco Signed-off-by: Paolo Valente --- block/bfq-cgroup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index b3796a40a61a..59f46904cb11 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -1046,7 +1046,8 @@ struct blkcg_policy blkcg_policy_bfq = { struct cftype bfq_blkcg_legacy_files[] = { { .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, + .link_name = "weight", + .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED, .seq_show = bfq_io_show_weight, .write_u64 = bfq_io_set_weight_legacy, }, @@ -1166,7 +1167,8 @@ struct cftype bfq_blkcg_legacy_files[] = { struct cftype bfq_blkg_files[] = { { .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, + .link_name = "weight", + .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED, .seq_show = bfq_io_show_weight, .write = bfq_io_set_weight, }, -- 2.20.1